Apache is a free and open-source cross-platform web server software.
Mod_rack is a free web server and application server with support for Ruby, Python and Node.js.
Mod_rails is a free web server and application server with support for Ruby, Python and Node.js.
Phusion Passenger is a free web server and application server with support for Ruby, Python and Node.js.
Ruby on Rails is a server-side web application framework written in Ruby under the MIT License.